EFFECTS OF DIETARY CORN AND OLIVE OIL VERSUS COCONUT FAT ON BILIARY CHOLESTEROL SECRETION IN RATS

We have studied the effects of dietary corn and olive oil versus cocon ut fat on bile formation and fluidity of hepatic plasma membranes in r ats. After 4 weeks of feeding the purified diets containing 9% (w/w) o f the test fats, there was no difference in plasma cholesterol concent ration between the dietary groups. The amount of free and esterified c holesterol in the liver was significantly higher in rats fed either co rn oil or olive oil as compared with coconut fat. In the rats fed oliv e oil, but not in those fed corn oil this was associated with lower ra tes of biliary phospholipid excretion. Bile flow was not differently i nfluenced by the three dietary fats. Hepatic plasma membranes of the r ats fed corn or olive oil contained more cholesterol and less phosphol ipids than those on coconut fat, which was, however, not accompanied b y changes in fluidity of the membranes. These results indicate that in rats the type of dietary fat can induce considerable changes in hepat ic cholesterol metabolism without affecting plasma cholesterol concent rations, and without consistent effects on biliary cholesterol secreti on.